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<?xml version='1.0' encoding="UTF-8"?>
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<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
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<guide link = "/doc/en/alsa-guide.xml">
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<title>Gentoo Linux ALSA Guide</title>
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<author title="Author"><mail link="zu@pandora.be">
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Vincent Verleye</mail>
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</author>
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<author title="Author"><mail link="g2boojum@gentoo.org">
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Grant Goodyear</mail>
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</author>
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<author title="Author"><mail link="agenkin@gentoo.org">
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Arcady Genkin</mail>
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</author>
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<author title="Editor"><mail link="zhen@gentoo.org">
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John P. Davis</mail>
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</author>
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<author title="Editor"><mail link="swift@gentoo.org">
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Sven Vermeulen</mail>
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</author>
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<license/>
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<abstract>
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This guide will show you how to set up the Advanced Linux Sound Architecture (ALSA) on Gentoo Linux.
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In addition to the Gentoo Linux Desktop Configuration Guide, this guide is supposed to give you more information on this subject. </abstract>
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<version>1.2</version>
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<date>5 June 2003</date>
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<chapter>
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<title>Introduction</title>
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<section>
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<title>What is ALSA?</title>
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<body>
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<p>
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The Advanced Linux Sound Architecture (ALSA) is a project to improve the Linux sound subsystem by rewriting
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large chunks of it.
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It is anticipated that ALSA will make it into Linux kernel 2.6.x (or 3.x.x -- whichever comes first) as it becomes ready.
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</p>
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<p>
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ALSA provides audio and MIDI functionality for Linux.
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</p>
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<p>
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Quoted from <uri>http://www.alsa-project.org</uri>, ALSA has the following features:
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<ul><li> Efficient support for all types of audio interfaces, from consumer soundcards to professional multichannel audio interfaces.</li>
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<li> Fully modularized sound drivers.</li>
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<li> SMP and thread-safe design.</li>
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<li> User space library (alsa-lib) to simplify application programming and provide higher level functionality.</li>
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<li> Support for the older OSS API, providing binary compatibility for most OSS programs.</li>
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</ul>
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There's lots more to ALSA however, like support for Full Duplex playback and recording, multiple soundcard support,
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hardware mixing of streams, extensive mixer capabilities (to support advanced features of new soundcards), ...
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</p>
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</body>
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</section>
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<section>
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<title>Why use ALSA?</title>
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<body>
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<p>
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If your soundcard is supported by the Linux kernel sound system or the commercial OSS/4Front sound driver system,
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which can be found in all 2.4.x Linux kernels, you could just aswell build <e>those modules</e> for use with your soundcard.
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If you want this, just read through the <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri>.
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</p>
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<p>
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However, those OSS/4Front drivers have some limitations -- being commercial is one.
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ALSA is an attempt to go beyond these limitations and to do so in an open source fashion.
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ALSA is a fully GPL and LGPL'ed sound driver system, that provides a professional quality system for recording, playback,
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and MIDI sequencing.
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</p>
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</body>
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</section>
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<section>
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<title>What cards does ALSA support?</title>
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<body>
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<p>
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ALSA tries to support as many (new) cards as possible by providing open-source drivers.
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However, some vendors may provide binary-only packages.
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</p>
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<p>To know if your card is supported, you can find a Soundcard Matrix of supported and not-supported cards here:
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<uri>http://www.alsa-project.org/alsa-doc/</uri>.
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</p>
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</body>
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</section>
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</chapter>
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<chapter>
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<title>Installation</title>
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<section>
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<title>Kernel modules</title>
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<body>
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<p>
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Since we're still using 2.4.x kernel sources, we'll have to compile kernel modules and ALSA modules separately. People who are using a 2.5.x kernel can do this from within their kernel configuration, since the ALSA modules are included in the kernel sources and should be built there.
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</p>
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<p>
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First we'll make sure that our kernel configuration is ready for use with ALSA.
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All you need in your kernel configuration is having Sound Card Support set to be built as a module (M).
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This will build <c>soundcore.o</c>.
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</p>
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<p>
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<note>
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Possibly, this will also work when you built Sound Card Support in the kernel (Y) instead of building it as a module (M).
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However, the official ALSA documentation suggests building it as a module, since ALSA will try loading it.
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</note>
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</p>
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<p>If you already have a working kernel configuration, make sure you remove all sound drivers (except for Sound Card Support).
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If you wish to do this without having to reboot, you could do like this:
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</p>
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<pre>
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# <c>cd /usr/src/linux</c>
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# <c>cp .config ~/</c>
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# <c>make mrproper</c>
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# <c>cp ~/.config .</c>
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# <c>make menuconfig</c>
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</pre>
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<p>
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Now select <e>Sound Card Support</e> as Module (M) and deselect all other sound drivers.
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Exit and say Y to save your kernel configuration.
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After that, build the modules:
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</p>
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<pre>
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# <c>make dep clean</c>
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# <c>make modules modules_install</c>
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</pre>
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<p>
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Before installing your new modules, this last line will delete all your previous modules,
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even the ones from a previous ALSA installation.
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</p>
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<p>
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<impo>
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This means, whenever you recompile your kernel later on, you MUST recompile <c>alsa-driver</c>.
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</impo>
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</p>
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<p>
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<note>However, there's no need to reinstall <c>nvidia-kernel</c>, the Nvidia drivers are in a separate directory
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in <path>/lib/modules/*/video</path> and won't get deleted by a <c>make modules modules_install</c>
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</note>
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</p>
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</body>
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</section>
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<section>
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<title>ALSA modules</title>
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<body>
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<p>
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Now it's time to install the ALSA drivers for your soundcard(s). If your soundcard is PCI, you can find out the name
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and type of your soundcard by looking at the output of /proc/pci
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<pre># <c>grep audio /proc/pci</c></pre>
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</p>
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<p>
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<warn>
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If you had a previous sound setup and there are still non-ALSA sound modules loaded, unload them <e>now</e>.
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Check with <c>lsmod</c> and use <c>rmmod</c> to unload all sound-related modules on your system.
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</warn>
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</p>
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<p>
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We could simply do an <c>emerge alsa-driver</c> now, this would compile and install <e>all</e> ALSA sound drivers.
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</p>
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<p>
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However, to save some time, lookup the <e>Module Name</e> of your soundcard(s) on the
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<uri link="http://www.alsa-project.org/alsa-doc">ALSA Soundcard Matrix</uri> by following the <e>Details</e> link in the <e>Driver and Docs</e> column in the row of the chipset of your soundcard.
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Mine is <c>snd-emu10k1</c>, since I have an SBlive! soundcard, with the <e>EMU10K1</e> chipset.
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We'll set ALSA_CARDS environment to the value of the module name before emerging (but without the snd prefix), so emerge will only compile the drivers we need.
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</p>
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<p>
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<pre>
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# <c>env ALSA_CARDS='emu10k1' emerge alsa-driver</c>
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</pre>
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</p>
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<p>
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<note>
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You can also add this value in <path>/etc/make.conf</path>, so when you have to emerge the alsa-driver later on you can just run <c>emerge alsa-driver</c>.
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For example, like this: <c>echo 'ALSA_CARDS="emu10k1"' >> /etc/make.conf</c>
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</note>
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<note>
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When you want to install ALSA drivers for more than one soundcard, you could set ALSA_CARDS to a space-separated list
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of drivers; like this: <c>env ALSA_CARDS='emu10k1 intel8x0 ens1370' emerge alsa-driver</c>
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</note>
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<note>If you want to have OSS compatibility, make sure to emerge <i>alsa-oss</i>, it is the ALSA/OSS compatibility
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wrapper. </note>
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</p>
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<p>
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After this, the ALSA modules should be installed on your system.
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</p>
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</body>
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</section>
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<section>
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<title>Configuration of ALSA</title>
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<body>
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<p>
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Let's start configuring now to get ALSA working properly.
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We'll need to edit some files, to let our system know about the freshly installed ALSA modules.
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</p>
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<p>
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First, install <c>alsa-utils</c> on your system:
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</p>
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<pre caption = "Emerging alsa-utils">
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# <i>emerge alsa-utils</i>
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</pre>
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<p>
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Hereafter, we need to edit <path>/etc/modules.d/alsa</path>.
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</p>
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<warn>
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There is no need to edit <path>/etc/modules.conf</path>. Instead, always edit files in <path>/etc/modules.d</path>.
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</warn>
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<p>
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Check the ALSA portion <e>at the bottom of the file</e>.
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By tweaking this line you can specify the max number of soundcards you have (generally, just one).
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</p>
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<p>
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<pre caption="At the bottom of /etc/modules.d/alsa">
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# Set this to the correct number of cards.
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<c>options snd cards_limit=1</c>
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</pre>
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</p>
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<p>
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Now we'll specify the sounddriver(s) ALSA should use. In the same file, edit like this:
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<pre caption="In /etc/modules.d/alsa">
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## and then run `update-modules' command.
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## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
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##
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## ALSA portion
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<c>alias snd-card-0 snd-emu10k1</c>
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<c>## If you have more than one, add:
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## alias snd-card-1 snd-intel8x0
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## alias snd-card-2 snd-ens1370</c>
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## OSS/Free portion
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## alias sound-slot-0 snd-card-0
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## alias sound-slot-1 snd-card-1
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##
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</pre>
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</p>
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<p>
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<note>
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If you have more than one soundcard, adjust the <c>cards_limit</c> value and add more snd-card aliases to the file.
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I don't have experience with this, but you can find examples for configurations with two or more soundcards in
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<uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/c1660.htm">Chapter 6</uri>
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of the <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/alsa-howto.html">ALSA Howto</uri>.
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</note>
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</p>
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<p>
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Last thing to do in this file, almost at the end, check if these lines are there and uncommented:
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<pre caption="Near the end of /etc/modules.d/alsa">
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alias /dev/mixer snd-mixer-oss
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alias /dev/dsp snd-pcm-oss
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alias /dev/midi snd-seq-oss
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</pre>
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</p>
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<p>
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Now double-check the file <path>/etc/modules.d/alsa</path> and when you're sure everyting is ok, run <c>update-modules</c>.
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<pre>
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# <c>update-modules</c>
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</pre>
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</p>
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<note>
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Running <c>update-modules</c> here will insert the data from <path>/etc/modules.d/alsa</path> into <path>/etc/modules.conf</path>
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</note>
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<p>
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You should also verify that /etc/devfsd.conf has the alsa devices and permissions correctly registered.
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</p>
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<pre caption="/etc/devfsd.conf">
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# ALSA/OSS stuff
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# Comment/change these if you want to change the permissions on
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# the audio devices
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LOOKUP snd MODLOAD ACTION snd
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LOOKUP dsp MODLOAD
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LOOKUP mixer MODLOAD
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LOOKUP midi MODLOAD
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REGISTER sound/.* PERMISSIONS root.audio 660
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REGISTER snd/.* PERMISSIONS root.audio 660
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</pre>
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<note>
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Notice that devfsd.conf sets /dev/sound permissions to be root.audio. Thus, for non-root users to use audio they will have to be part of the audio group.
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</note>
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</body>
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</section>
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</chapter>
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<chapter>
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<title>Starting ALSA</title>
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<section>
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<title>Adding alsasound to a runlevel</title>
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<body>
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<p>
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First thing to do now, is to make ALSA startup at boottime. Like this:
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<pre>
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# <c>rc-update add alsasound boot</c>
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</pre>
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</p>
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<p>
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<warn>Note that the alsasound script should be added to the "boot" runlevel, not the "default" runlevel.</warn>
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</p>
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</body>
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</section>
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<section>
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<title>Running and unmuting</title>
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<body>
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<p>
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Since we're Linux users, we don't want to reboot. So we'll start the alsasound script manually.
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</p>
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<pre>
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# <c>/etc/init.d/alsasound start</c>
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</pre>
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<p>
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ALSA is running now. If everything is ok, you should be able to see the ALSA modules loaded when running <c>lsmod</c>.
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However, sound won't work yet, because the channels are still muted. We need <c>amixer</c> for this.
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</p>
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<pre caption = "Running amixer">
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# <i>amixer</i>
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</pre>
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<p>
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<warn>
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You shouldn't get this, but <e>if</e> you get an error about "amixer: Mixer attach default error: No such file or directory", you should manually insmod
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<c>snd-mixer-oss</c> and <c>snd-pcm-oss</c> once. After that run amixer again.
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</warn>
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</p>
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<pre caption="only if you get an error when running amixer">
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# <c>insmod snd-mixer-oss</c>
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# <c>insmod snd-pcm-oss</c>
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# <c>amixer</c>
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</pre>
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<p>
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If you got this far, now unmute both Master and PCM channels.
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</p>
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<p>
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| 337 |
<pre>
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# <c>amixer set Master 100 unmute</c>
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# <c>amixer set PCM 100 unmute</c>
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# <c>aplay $KDEDIR/share/sounds/pop.wav</c> <codenote>(pop.wav is part of KDE)</codenote>
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</pre>
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</p>
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We check to see if sound is working by using the aplay (alsa play) command. If you hear a pop, then sound is indeed working.
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Then, adjust the volume settings to your liking; the ncurses-based <c>alsamixer</c> is a great way to get them "just so".
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<p>
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You may want to emerge <c>alsa-xmms</c> as that will provide ALSA support for XMMS.
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</p>
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When you reboot your system, the <e>alsasound</e> init script will properly save and restore your volume settings.
|
| 349 |
</body>
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| 350 |
</section>
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| 351 |
</chapter>
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| 352 |
<chapter>
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<title>Final Notes</title>
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| 354 |
<section>
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| 355 |
<title>After kernel-upgrades..</title>
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| 356 |
<body>
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| 357 |
<p>When you ever rebuild your kernel, or upgrade to another kernel, you'll have to rebuild the ALSA modules.</p>
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<p>Although you might have installed <c>alsa-driver</c>, <c>alsa-libs</c> and <c>alsa-utils</c>, only the first will
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have to be installed again, since it will put the alsa modules in
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<path>/lib/modules/*/kernel/sound/pci/</path>.</p>
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| 361 |
<pre caption="needed after each kernel compile">
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| 362 |
# <c>emerge alsa-driver</c>
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| 363 |
</pre>
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| 364 |
</body>
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| 365 |
</section>
|
| 366 |
<section>
|
| 367 |
<title>/etc/modules.autoload</title>
|
| 368 |
<body>
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| 369 |
<p>You won't have to edit this file for use with ALSA. After our <c>rc-update add alsasound boot</c>, our system will
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load the correct modules at startup.</p>
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<p>It's not necessary to add <c>snd-pcm-oss</c> or <c>snd-mixer-oss</c> in this file.
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Check the <uri link="http://www.djcj.org/LAU/guide/alsbook/faq1.html">this FAQ</uri> for more info.</p>
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| 373 |
</body>
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| 374 |
</section>
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| 375 |
<section>
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| 376 |
<title>More links..</title>
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| 377 |
<body>
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| 378 |
<p>
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| 379 |
You could check these for additional info:
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</p>
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<p>
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<ul>
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<li><uri link="http://www.gentoo.org/doc/en/desktop.xml">The Gentoo Linux Desktop Configuration Guide</uri></li>
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<li><uri link="http://www.alsa-project.org">ALSA Project Homepage</uri></li>
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<li><uri link="http://www.alsa-project.org/documentation.php3">ALSA Users Documentation</uri></li>
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<li><uri link="http://www.djcj.org">ALSA Howto's and FAQ's</uri></li>
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<li><uri link="http://tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri></li>
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<li><uri link="http://linux-sound.org/">Sound and MIDI Software For Linux</uri></li>
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</ul>
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</p>
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| 391 |
</body>
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| 392 |
</section>
|
| 393 |
</chapter>
|
| 394 |
</guide>
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